It is conventional to support ceiling panels in a grid of T-bars, generally spaced on 2' centers. The ceiling panels are installed by turning them diagonally, pushing them up into the space above the plane defined by the horizontal elements of the T-rails, turning them to orient them properly, and dropping them onto the upper surface of the horizontal ledge of the T-rail. The ceiling panels have sometimes been provided with an off-set or rabbet along each edge, to facilitate their orientation and to make them either flush with the lower surface of the T-rail or even to project a short distance below that T-rail surface. In any event, the T-rails themselves are still in evidence, and the decorative effect is limited. It has not been possible with this type of ceiling to give the effect of an unbroken expanse.
Attempts have been made to provide ceilings made up of panels that still gave the impression of continuous surface, but they have involved metal panels or metal frames for panels, and have been somewhat complicated to make and use. See, for example, U.S. Pat. Nos. 4,760,677 and 4,291,783.
One of the objects of this invention is to provide a plastic panel constructed to permit the installation of a multiplicity of such panels in a grid of rails, in which contiguous panels abut so as to obscure the joint between them.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.